This solution applies to Spam Firewalls, all firmware versions.
Setting up HTTPS in the Spam Firewall product is done on the Advanced > Secure Administration page of the Barracuda's Web user interface. Under Web Interface HTTPS/SSL Configuration will list HTTPS/SSL access only. Click on "YES" to allow only https to be able to connect to the web interface.
Note: You must be logged into the device with admin account using https://( IP )